The present invention relates to a novel medicament capsule for rectal application. More particularly, the invention relates to a medicament form of a hard capsule made of a novel enterosoluble cellulose derivative encapsulating a therapeutically effective ingredient capable of being absorbed through the rectum.
As is well known, a variety of medicines are used in a medicament form suitable for rectal application with an object either to obtain a systemic action or to obtain a local action of the effective ingredient. Several of the examples of the medicaments of which a systemic action is desired by the rectal application include antipyretic, anodynic and antiphlogistic agents such as aspirin, aminopyrine, sulpyrin, phenylbutazone, oxyphenbutazone, indometacin and the like, antispasmodic agents such as butyl scopolamine bromide and the like, antibiotics such as erythromycin and the like, anti-tuberculosis agents such as ethionamide and the like, and others. Those medicines of which a local action is desired include, on the other hand, astrigents, local anesthetics and bactericidal agents with or without admixture of an adrenocortical hormone for haemorrhoids.
At any rate, the effective ingredient in the medicine administrated by rectal application is directly absorbed in the venous plexus of the rectum to be distributed throughout the body by the blood circulation without passing the portal vein and the liver. Therefore, a rectally applicable medicament form is preferable particularly for the medicines of which the effective ingredient causes a disorder in the stomach when orally administrated or the ingredient is susceptible to decomposition in the digestive tract or in the liver resulting in decreased effectiveness of the medicine.
As is well known, the medicament forms for rectal application in general include suppositories ans so-called rectal capsules.
Suppositories as a medicament form are prepared usually by dispersing the therapeutically active ingredient in a base such as cacao butter, polyethyleneglycol, mixture of higher fatty acid glycerides and the like solidifying and shaping the blend into a desired form, e.g. a conical or cannonball-like form, suitable for insertion into the coelom through the anus. Suppositories are the most widely used medicament form for rectal application and effective by releasing the effective ingredient in the rectum when melted at the body temperature or dissolved in the rectal fluid.
Suppositories present a very convenient means for rectal application of the medicine but not without various problems in the preparation and storage thereof. Several of the problems are that an efficient means is required for the uniform dispersion of the effective ingredient in the highly consistent suppository base, that suppositories are not a suitable medicament form for an ingredient susceptible to thermal decomposition because the ingredient must be distributed in the base molten by heating, that suppositories must be stored in a cool place because deformation of suppotitories is unavoidable at a relatively high temperature and that specific facilities are necessary for the preparation thereof to be in compliance with the aforementioned problems.
On the other hand, a rectal capsule is a modification of the supporitory in a sense and can be prepared in a manner similar to the preparation of soft capsules. That is, the therapeutically effective ingredient, alone or with admixture of other additives according to need, is shaped by lightly compressing and encapsulated and further shaped with a capsule base such as gelatin. Therefore, preparation of rectal capsules also requires specific facilities and skillful works.
In view of the above problems in the rectal capsules, it is another possible way to utilize an ordinary gelatin-made capsule for oral administration as the medicament form for retal application. Several difficulties are, however, encountered in the use of gelatin capsules for rectal application. For example, medicines with acidity or in an aqueous liquid form cannot be encapsulate in both hard and soft gelatin-made capsules. Further, powdery medicines encapsulated in an soft capsule are not free from the problem in the stability in addition to the burdensomeness in the preparation of the medicament form.
Accordingly, it has been eagerly desired to develop a medicament capsule for rectal application easy to prepare into the medicament form with excellent stability during storage and capable of uniform disintegrability in the rectum and the absorbability of the effective ingredient through the rectum.